Gene Ontology annotation based on UniPathway vocabulary mapping
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Electronic Gene Ontology annotations created by ARBA machine learning models
FKF1, a clock-controlled gene that regulates the transition to flowering in Arabidopsis.
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Original positional cloning of FKF1 from a late-flowering Arabidopsis mutant; FKF1 encodes a protein with a PAS/LOV flavin-binding photoreceptor domain, an F-box motif, and six kelch repeats predicted to fold into a beta-propeller, defining the ADO/FKF/LKP/ZTL family architecture.
"We positionally cloned FKF1, which encodes a novel protein with a PAS domain similar to the flavin-binding region of certain photoreceptors, an F box characteristic of proteins that direct ubiquitin-mediated degradation, and six kelch repeats predicted to fold into a beta propeller."
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FKF1 mRNA levels oscillate with a circadian rhythm and FKF1 deletion alters the waveform of two clock-controlled genes, implicating FKF1 in modulating the Arabidopsis circadian clock.
"FKF1 mRNA levels oscillate with a circadian rhythm, and deletion of FKF1 alters the waveform of rhythmic expression of two clock-controlled genes, implicating FKF1 in modulating the Arabidopsis circadian clock."
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The fkf1 mutant late-flowering phenotype is rescued by vernalization or gibberellin treatment, placing FKF1 specifically in the photoperiodic flowering pathway rather than in the vernalization or gibberellin pathways.
"We isolated a late-flowering Arabidopsis mutant, fkf1, that is rescued by vemalization or gibberellin treatment."
Protein degradation in signaling.
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Review describing how ubiquitin/proteasome-mediated proteolysis in higher plants connects to hormone responses, light perception, environmental adaptation, and floral development; cited as a TAS source for FKF1's ubiquitin-dependent catabolic role.
"Recent studies have linked proteolysis by the ubiquitin/proteasome pathway to a variety of signaling pathways in higher plants."
Expression and interaction analysis of Arabidopsis Skp1-related genes.
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Yeast two-hybrid screen establishes that ASK1, ASK2, ASK11 and ASK12 interact directly with FKF1 (and other F-box proteins), supporting assembly of SCF(FKF1) complexes.
"ASK1, ASK2, ASK11 and ASK12 interacted well with COI1, FKF1, UFO-like protein, LRR-containing F-box proteins, and other F-box proteins with unknown C-terminal motifs."
Identification of ASK and clock-associated proteins as molecular partners of LKP2 (LOV kelch protein 2) in Arabidopsis.
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LKP2 interacts with FKF1 and LKP1 in yeast two-hybrid, demonstrating that members of the ADO/FKF/LKP/ZTL LOV-F-box-Kelch family form hetero- and homo-typic interactions, with the LOV domain being necessary and sufficient for TOC1 binding by LKP2.
"LKP2 interacted not only with itself but also with other members of the family, LKP1 and FKF1."
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Members of the ADO/FKF/LKP/ZTL family interact with ASK/Skp1-like proteins to assemble SCF E3 ligase complexes, framing FKF1 as a substrate-recognition F-box of an SCF complex.
"LKP2 interacted with some Arabidopsis Skp1-like proteins (ASK), as do other ADO/FKF/LKP/ZTL family proteins, suggesting that LKP2 can form an SCF (Skp1-Cullin-F-box protein) complex that functions as a ubiquitin E3 ligase."
FKF1 F-box protein mediates cyclic degradation of a repressor of CONSTANS in Arabidopsis.
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FKF1 physically interacts with the Dof transcription factor CYCLING DOF FACTOR 1 (CDF1), targets it for proteasomal degradation, and thereby relieves CDF1-mediated repression of CONSTANS (CO); CDF1 protein is more stable in fkf1 mutants and elevated CDF1 levels reduce CO expression and delay flowering.
"We demonstrate here that FKF1 controls the stability of a Dof transcription factor, CYCLING DOF FACTOR 1 (CDF1). FKF1 physically interacts with CDF1, and CDF1 protein is more stable in fkf1 mutants. Plants with elevated levels of CDF1 flower late and have reduced expression of CO."
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FKF1 controls daily CO transcription in part by degrading the CDF1 repressor of CO transcription, establishing the FKF1-CDF1-CO regulatory axis that times photoperiodic flowering.
"FKF1 controls daily CO expression in part by degrading CDF1, a repressor of CO transcription."
ZEITLUPE is a circadian photoreceptor stabilized by GIGANTEA in blue light.
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Defines the family blue-light/LOV-GIGANTEA paradigm: ZTL-GI interaction is strongly and specifically enhanced by blue light through ZTL's N-terminal LOV domain, with GI stabilizing ZTL in vivo - this paradigm directly informs FKF1's analogous LOV-dependent, blue-light-enhanced interaction with GI.
"the ZTL-GI interaction is strongly and specifically enhanced by blue light, through the amino-terminal flavin-binding LIGHT, OXYGEN OR VOLTAGE (LOV) domain of ZTL."
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GIGANTEA-mediated stabilization sustains oscillations of LOV-F-box family proteins, with mutations in the LOV domain (e.g. C82A) diminishing the interaction and reducing protein levels - paralleling the LOV-dependent interaction reported for FKF1-GI.
"GIGANTEA (GI) is essential to establish and sustain oscillations of ZTL by a direct protein-protein interaction."
FKF1 and GIGANTEA complex formation is required for day-length measurement in Arabidopsis.
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FKF1 and GIGANTEA (GI) proteins form a complex in a blue-light-dependent manner; the timing of this interaction in the late afternoon under long days regulates the timing of daytime CO transcription, providing the molecular basis for day-length measurement.
"We demonstrate that FKF1 and GI proteins form a complex in a blue-light-dependent manner. The timing of this interaction regulates the timing of daytime CO expression."
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FKF1, GI, and CDF1 all associate with CO chromatin; FKF1-GI complex formation on the CO promoter in late afternoon coordinates light coincidence with circadian timing to regulate photoperiodic flowering.
"GI, FKF1, and CDF1 proteins associate with CO chromatin. Thus, the FKF1-GI complex forms on the CO promoter in late afternoon to regulate CO expression, providing a mechanistic view of how the coincidence of light with circadian timing regulates photoperiodic flowering."
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FKF1 function is dependent on GI, which interacts with the CO repressor CYCLING DOF FACTOR 1 (CDF1) and controls CDF1 stability, embedding the FKF1-CDF1-CO axis within a larger GI-dependent module.
"FKF1 function is dependent on GI, which interacts with a CO repressor, CYCLING DOF FACTOR 1 (CDF1), and controls CDF1 stability."
Evidence for network evolution in an Arabidopsis interactome map.
FKF1 conveys timing information for CONSTANS stabilization in photoperiodic flowering.
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FKF1 directly interacts with CO protein through its LOV domain in a blue-light-enhanced manner and stabilizes CO in the late afternoon of long days, providing a second (post-translational) mechanism by which FKF1 promotes CO function.
"we demonstrate that FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 (FKF1) protein stabilizes CO protein in the afternoon in long days. FKF1 interacts with CO through its LOV domain, and blue light enhances this interaction."
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FKF1 simultaneously removes the CDF1 repressor of CO and FT transcription while stabilizing CO protein, integrating multiple feedforward mechanisms that ensure robust FT mRNA induction and accurate timing of flowering.
"FKF1 simultaneously removes CYCLING DOF FACTOR 1 (CDF1), which represses CO and FLOWERING LOCUS T (FT) transcription. Together with CO transcriptional regulation, FKF1 protein controls robust FT mRNA induction through multiple feedforward mechanisms that accurately control flowering timing."
A comprehensive analysis of interaction and localization of Arabidopsis SKP1-like (ASK) and F-box (FBX) proteins.
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Comprehensive yeast two-hybrid plus in vivo interaction and subcellular localization analysis of Arabidopsis ASK x F-box pairs documents which ASKs assemble with FKF1 and related Kelch-domain F-box proteins, supporting SCF(FKF1) complex assembly.
"we carried out a large-scale interaction analysis between FBX and ASK proteins using yeast two-hybrid assay (Y2H) in Arabidopsis thaliana. FBX proteins randomly chosen from those proteins that interacted with more than one ASK protein were further analyzed for their subcellular localization and in vivo interaction with ASK proteins."
The Photoperiodic Flowering Time Regulator FKF1 Negatively Regulates Cellulose Biosynthesis.
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Genetic suppressor screen using the cellulose-deficient c1,c3 (cesa1aegeus,cesa3ixr1-2) mutant identifies FKF1 as a negative regulator of cellulose biosynthesis - a secondary, pleiotropic FKF1 role beyond photoperiodic flowering.
"Here, we characterize the role of FLAVIN-BINDING KELCH REPEAT, F-BOX 1 (FKF1), another blue light receptor and well-known photoperiodic flowering time regulator, in cellulose biosynthesis. A phenotype suppression screen using a cellulose deficient mutant"
FKF1 Interacts with CHUP1 and Regulates Chloroplast Movement in Arabidopsis.
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FKF1 physically interacts with the chloroplast outer-membrane protein CHUP1 (Y2H and BiFC) and modulates blue-light-driven chloroplast photorelocation (avoidance) in Arabidopsis - a secondary pleiotropic role with the molecular mechanism not yet resolved.
"This study discovered that another blue light receptor, FLAVIN-BINDING KELCH REPEAT F-BOX1 (FKF1), regulates chloroplast photorelocation by physically interacting with chloroplast unusual positioning protein 1 (CHUP1)"
Falcon/Edison deep research report: FKF1
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FKF1 is a blue-light-responsive LOV-domain photoreceptor combined with an F-box motif and Kelch-repeat substrate-recognition module; it functions as the substrate-recognition subunit of an SCF(FKF1) E3 ubiquitin ligase.
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FKF1 has two coupled photoperiodic functions: (i) blue-light-enhanced GI complex formation and CDF1 degradation on the CO promoter in late afternoon of long days, and (ii) direct LOV-mediated stabilization of CO protein in the late-afternoon long-day window, jointly driving FT expression.
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FKF1 mRNA peaks ~10 h after dawn under long days; this expression phasing, together with blue light availability, sets the long-day-specific window in which FKF1-GI complexes assemble on the CO promoter.
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Secondary FKF1 roles include negative regulation of cellulose biosynthesis (PMID:31221729) and modulation of chloroplast photorelocation via CHUP1 (PMID:36771626); these are pleiotropic and mechanistically less well established than the photoperiodic flowering function.